Marine stoker



H. P. ANDERSON MARINE STOKER Filed April 22, 1932 2 Sheets-Sheet l \w WW A lllliliiliir 2, fmv m RWUWHHHMU 1.1, H

ATTORNEY.

May 5, 1196. H. P. ANDERSON 1,

MARINE STOKER Filed April 22, 1932 2 Sheets-Sheet 2 ATTORNEY.

Patented May 5, 1936 UNITED STATES PATENT OFFICE MARINE STOKER Application April 22, 1932, Serial No. 606,869

6 Claims.

This invention relates to stokers of the type which supply fuel to a plurality of furnaces such as the furnaces of the Scotch boiler used in maritime service and has for its chief object the provision of a stoker which is arranged to fire each furnace independently of the other furnaces.

Another object of this invention is the provision of a stoker for firing a'plural'ity of furnaces of a common boiler from a point above the furnace grates, the stoker comprising a series of fuel conveyors each of which is independently operated by a separate driving unit whereby the amount of fuel fed to each furnace is readily controlled and the driving unit easily removed and repaired.

It is also an object of this invention to provide a stoker for firing a plurality of furnaces of a common boiler in which the outermost furnaces are disposed at a greater elevation than the inner furnaces, the stoker comprising a plurality of upright elevators, one for each of the elevated furnaces, which conveys fuel to a distributor passing through the boiler front wall into its respective furnace, and a fuel elevator for delivering fuel to a furnace which is below the level of the elevated furnaces, this fuel elevator delivering fuel into such furnace through the grate thereof.

Other objects and advantages of this invention, such as the novel mounting of the stoker with respect to the furnace or boiler front wall and the boiler room structure of a vessel, will become apparent when the following specification is read in connection with the accompanying drawings, in which Figure l is a central vertical longitudinal section through'a marine boiler showing the fuel bunker in similar section and the stoker mechanism in elevation, a portion of which has been removed;

Figure 2 is a sectiontaken on the line 2-2 of Figure 1;

Figure 3 is a section taken on the line 33 of Figure 1;

Figure 4 is a section taken on the line 4-4 of Figure 3 with portions of the stoker broken away to best illustrate the structure; and

Figure 5 is a view similar to a portion of Figure 1 showing a modified form of the invention, parts of which are in central vertical longitudinal section.

The term forward, as employed in the description, denotes the general direction in which the fuel flows from the bin to the furnaces.

Referring now to Figures 1 to 4 inclusive, which illustrate the preferred embodiment of the invention, the boiler room of a vessel is generally indicated at I having a firing floor II, the fuel bunker I2 and a battery of boilers such as I3.

Each of the boilers I3 is provided with a plurality of furnaces such as I4, I and I6, although it will be readily understood that any number of furnaces may be used. The central furnace I5 is usually below the level of the outermost furnaces I 4 and I6. Each of the furnaces consists of a drum I1, the fire grate I8 and the furnace rear wall I9 which is provided with doors and 2I through which hand firing and ash removal respectively is effected. The products of 15 combustion pass from the furnaces into the breeching 22 and then out through the stack (not shown).

The stoker mechanism for feeding fuel from the bunker I2 to thefurnaces is generallyindicated at S and comprises a transfer conveyor T,

a hopper H, and a plurality of fuel elevators E.

The transfer conveyor T consists of a trough 23 which receives fuel from the bunker I2, a tubular member 24 extending forwardly from the trough 23 and discharginginto the hopper H, and a conveyor screw 25 rotatably mounted in the transfer conveyor T and substantially coextensive therewith. The trough 23 has formed therewith a foot member 26 through which it is secured to the plate member 21, disposed beneath the firing floor I I and forming therewith a compartment 28. Suitable means are provided for operating the conveyor screw 25 and include the prime mover 29, located in the compartment, which transmits power through shafting 39 to gearing (not shown) in the gear housing 3| for driving the conveyor screw in a'well known manner.

The hopper H comprises a rearward portion 32 and a forward portion 33 which portions are secured to each other through the respective flanges 32a and 33a. The rearward portion 32 is se' cured to the plate member 21 through the feet 34 and flares laterally as it extends toward said forward portion 33. The forward portion 33 of the hopper H is provided with the flanges 35 at its upper portion to which are secured the flanged casings 36 enclosing the conveyor screws 31 of the elevators E. The lower portion 38 of each of the screws 31 extends into the hopper H and elevates the fuel received therefrom to a distributor D which extends freely into the furnace through the firing opening 39 of the furnace rear wall I9. The fuel distributor comprises a tubular member 40 which is supported in the recess 4| of the elevator E. At its forward end the distributor D is provided with the top defiector 42 and the bottom deflector 43 which serve to direct fuel evenly to all parts of the fire grate I8 as projected through the tubular member 40 by pressure fluid issuing from the nozzle 44.

The conveyor screws 31 are each driven independently from their upper ends by a driving unit such as 45 which consists of a housing 46 mounted upon the upper end of the flanged casing 36. A motor 41 secured to a fiange 48 of the housing 46 transmits power to the reduction gearing 49 through the shaft 50. The reduction gearing 49 is operatively connected to the conveyor screw 31 of each of the elevators E, and each screw is operated at the desired rate of speed by controlling the speed of the motor 41 of its driving unit.

In the operation of the preferred form of this invention, fuel falls by gravity into the trough '23 of the transfer conveyor T. The screw 25 therein advances the fuel forwardly and discharges the fuel into the hopper H at a rate suflicient to allow the hopper to be filled with fuel at all times. The fuel from the hopper H is then received by the screws 31 of the elevators E, each elevator being driven at a suitable rate of speed by its respective driving unit 45 so as to feed the required amount of fuel into each furnace. The elevators E deliver the fuel to a dis tributor D which extends freely through the firing opening 39 in the furnace rear wall I 9. A nozzle 44 issues blasts of pressure fiuid against the fuel thus delivered and distributes the fuel to all parts of the furnace grate as controlled by the fuel deflectors 42 and 43.

By providing separate driving means for the transfer conveyor and each of the elevators, a stoker has been provided in which the delivery of fuel to any furnace may be varied independently of the delivery to the other furnaces. By this construction, each of the driving units 45 is easily accessible and removable for the purpose of repairs and the fuel elevators each deliver fuel to a point of distribution without obstructing the furnace doors or without impeding the free movement of workmen in the boiler room. The mounting of the stoker rigidly to the plate member below the firing deck and loosely with respect to the boiler I3 is also advantageous in that any weaving or buckling of the vessel structure will not be transmitted to the boiler by the stoker, thereby preventing any breakage of parts which would occur if the stoker is rigidly secured to the boiler.

In the modified form of this invention shown in Figure 5, the hopper H at its forward portion is provided with a forwardly inclined conduit or elevator 60 which terminates in an upturned elbow 5| passing through the fire grate l8 into a furnace intermediate the outermost furnaces of the boiler. A head 52 issues jets of pressure fiuid across the table 53 of the elbow 5| and projects the fuel to all parts of the fire grate as the fuel in this elbow is elevated by the screw 54 in the inclined conduit 60. A driving unit 55, similar to the driving unit 45 of the preferred form 'of the invention, operates the screw 54 from its lower end and is received in a compartment 56 below the plate member 21. It will be understood that any number of such inclined conduits '60 may be employed, and if found desirable or practicable, all furnaces may be so fired. However, it is more desirable to fire only the centrally located furnace in this manner, inasmuch as these furnaces are usually lower than the outermost furnaces, and hence, do not require the use of an unusually long elbow through which the fuel must be forced.

From the foregoing description, it is apparent that a stoker has been provided which is especially useful in marine service with Scotch boilers and which is efiicient in operation, easily controlled and readily accessible for the purpose of repairs.

I claim:

1. In combination, a boiler having a plurality of furnaces, a fire grate in each of said furnaces, a source of fuel supply, a single transfer conveyor leading from said fuel supply and terminating below the level of said fire grates, drive means for said transfer conveyor including a variable speed prime mover, a plurality of feed conduits communicating with and extending upwardly from said transfer conveyor, each of said feed conduits delivering to a respective furnace of the boiler, conveying means in each of said feed conduits for elevating fuel therethrough to a point above the level of the fire grates, and means including a variable speed prime mover for each conduit, said means arranged to drive the conveying means of each conduit independently of the conveying means of the other conduits and. independently of said transfer conveyor. the variable speed prime movers of said fuel elevators being free of operative connection with each other and with the variable speed prime mover of said transfer conveyor whereby the rate of fuel feed to any furnace may be varied without affecting the rate of feed to the other furnaces.

2. In combination, a boiler having a plurality of furnaces disposed in an upper elevation and a furnace disposed at a lower elevation, a fire grate in each of said furnaces, a source of fuel supply, a single transfer conveyor leading from said fuel supply and terminating at a point below the level of said fire grates, a plurality of feed conduits communicating with and extending upwardly from said transfer conveyor, each of said feed conduits delivering to a respective furnace, the feed conduits of said upper furnaces leading forwardly thereto from a point exterior of said furnaces to a point above the grates thereof and the feed conduit of the lower furnace leading upwardly thereto through the fire grate thereof and extending thereabove, containing means in each of said feed conduits for elevating fuel therethrough, and means for driving the conveying means of each conduit independently of the conveying means of the other conduits.

3. In combination, a boiler having a plurality of furnaces, a fire grate in each of said furnaces, a fuel bunker, a stoker comprising a transfer conveyor leading from said bunker and terminating below the level of said fire grates, a plurality of feed conduits communicating with and extending upwardly from said transfer conveyor, each of said feed conduits delivering to a respective furnace of the boiler, conveying means in each of said feed conduits for elevating fuel therethrough to a point above the level of the fire grates, means at the delivery end of each of said feed conduits for projecting and distributing fuel in aerial paths in each of said furnaces, a variable speed prime mover for operating said transfer conveyor and a driving unit including a variable speed prime mover for operating each of said fuel elevators independently of the others ilk and independently of said fuel transfer conveyor, the variable speed prime movers of said fuel elevators being free of operative connection with each other and with the variable speed prime mover of said transfer conveyor whereby the rate of fuel feed to any distributing and projecting means may be varied without affecting the rate of feed to the other distributing and projecting means.

4. In combination, a boiler having a plurality of furnaces, a fire grate in each of said furnaces, a fuel bunker, a stoker comprising a transfer conveyor leading from said bunker and terminating below the level of said fire grates, a plurality of feed conduits communicating with and extending upwardly from said transfer conveyor, each of said feed conduits delivering to a respective furnace of the boiler, one of said feed conduits extending above the grates and feeding into its respective furnace from a point ex terior thereto, and another of said feed conduits extending into the furnace through the fire grate to a point thereabove, conveying means in each of said feed conduits for elevating fuel therethrough to a point above the level of the fire grates, means at the delivery end of each of said feed conduits for projecting and distributing fuel in aerial paths in each of said furnaces, a variable speed prime mover for operating said transfer conveyor and a driving unit including a variable speed prime mover for operating each of said fuel elevators independently of each other and independently of said fuel transfer conveyor whereby the rate of fuel feed to any distributing and projecting means may be varied without affecting the rate of feed to the other distributing and projecting means.

5. In combination, a boiler having a plurality of furnaces comprising a pair of furnaces disposed at a greater elevation than the remainder of said furnaces, a fire grate for each of said furnaces, a front wall for said boiler provided with a firing opening therein for each of said upper furnaces, a fuel bunker, a stoker including a transfer conveyor receiving fuel from said bunker, a hopper for receiving fuel from said transfer conveyor, a plurality of upright elevators each receiving fuel from said hopper and delivering the same to the firing opening of its respective upper furnace, elevating means receiving fuel from said hopper and delivering the same to the lower of said furnaces, said elevating means delivering the fuel through the fire grate of the lower of said furnaces to a point of distribution above the grate thereof, and means for driving said transfer conveyor and said elevators and elevating means separately and independently of each other.

6. In combination, a boiler having a plurality of furnaces comprising a pair of furnaces disposed at a greater elevation than the remainder of said furnaces, a fire grate for each of said furnaces, a front wall for said boiler provided with a firing opening therein for each of said upper furnaces, a fuel bunker, a stoker including a transfer conveyor receiving fuel from said bunker, a hopper for receiving fuel from said transfer conveyor, a plurality of upright elevators each receiving fuel from said hopper and delivering the same to the firing opening of its respective upper furnace, elevating means receiving fuel from said hopper and delivering the same to the lower of said furnaces, said elevating means comprising a forwardly inclined conduit terminating in an upturned elbow that extends into the lower of said furnaces through and above the fire grate thereof and a conveyor screw in said forwardly inclined conduit for elevating the fuel through said upturned elbow to a point of distribution above the level of the grate, and means for driving said transfer conveyor and said elevators and elevating means separately and independently of each other.

HOWARD P. ANDERSON. 

